GRAMINEiE. (GRASS FAMILY.) 625 



++ -H- Rhachis bearing a rudimentary second flower or short bristle (except in species of 



n. 33). 

 32. Apera. Flmvering glutiie bifid, awned. Panicle very loose and delicate. 

 3:i. Calaiuagrostis. Flowera hairy-tufted at base. Glume.s menibranaceoua. Palet thln. 

 ■ 'A. Aininophila. Spilcelets large. Flowci-s hairy-tufted al ba.so. Glumes and palet 



cliaitaceous. 

 Tribe VII. AVENEiE. Spikelets 2 -several-flowered, panicled, the rhachis or base 

 of the flowei-s often bearded ; upper flower imperfect or rudiment«iry (except in n. 37). 

 Flowering glume bearing a twisted, bent or straight awn on its back or liclow the apex. 



• One of the flowers staminate only. 



35. Arrhenatheruiu* Lower flower staminate, long-awned ; middle flower perfect, nearly 



awnless; tlie upper rudimentary. 



36. Holcus. Flowers 2, the lower perfect, awnless, the upper staminate, awned. 



* * Flowers all perfect or the uppermost usually rudimentary. 



37. Aira. Spikelets very small, in a diflfuse panicle. Flowers 2, perfect, awned toward 



the base. 



38. Deschampsia. Spikelets 2-flowered, with a hairy rudiment Glumes thin-scarious, 



tlic flowering one erose-truncate, awned near the uiiddle. 



39. Trisetutn. Spikelets 2 -several-flowered. Flowering glume thin, compressed, cari- 



nate, 2-toothed, awned above by the excurrcnt mid-nerve. 



40. Avena. Spikelets 2-. several-flowered. Flowering glume hard and firm, rounded on 



the back, 5-9-nerved, the mid-nerve long-excurrent at or below the 2-toothed apex. 



41. Danthonia. As Avena, hut the 3 middle nerves of the flowering glume running into 



a flattish twi.sted awn from between the teeth. 

 Tribe VIII. CHLORIDES. Spikelets 2 -several-flowered with one or more of the 

 upper flowers imperfect (flower 1 and perfect in n. 45), arranged In 2 rows upon tho 

 rhachis of a 1-sided spike. 



* Spikelets with one perfect flower. 



42. Cynodon. Spikes 3-5, slender, digitate. Flower and the rudiment awnless. 



43. Ctenium. Spike solitary, terminal. Flowers 4-6, the middle one perfect 



44. Gymnopog:on. Spikes flliform, racemose. Spikelets remote, of a perfect flower and 



an awned rudiment. 



45. Scliedoiinardus. Spikes 3 - 9, slender, scattered, distant. Spikelets small, 1-flow- 



ered, awiiles.s, 



46. Bouteloua. Spikes scattered (rarely 1 and terminal), dense. Glume of perfect flower 



3-toothed. Rudimentary flowers 1-3-awned. 



* • Spikelets with two or more perfect flowers ; a%vns none. 



47. Eleusine. Spikes digitate, dense. 



48. Leptochioa. Spikes racemose, slender. Spikelets small, alternate. 



• * ♦ Spikelets dioecious; spikes small, very dissimilar, 



49. Buchloe. Pistillate spikes capitate, sessile, the spikelets 1-flowered ; staminate spikes 



(2 or 3) on a peduncle, the spikelets 2-3-flowered. 

 Tribe IX. FESTUCE.E. Spikelets few - many- flowered, panicled, the uppermost 

 flowers often imi>erfect or abortive. Glumes pointless or the flowering ones tipped with 

 a straight awn or bristle. 

 » Flowering glume 1 -3-nerved, 2 -3-toothed. Rhachis short-bearded or glabrous. 



50. Triodia. Rhachis of the spikelet bearded. Nerves of the flowering glume 3, villous, 



at least the middle one more or less excurrent. 



51. Diplachne. Rhachis glabrous. Glume 1- 3-nerved, with 2 small teeth, and a short 



awn in the cleft. 

 • • Glume 3-nerved, entire or 2-tootlied and mucronatc between the teeth. Rhachis and 

 flowers long-villous. Tall reeds with ample panicles. 



52. Phragniites. Spikelets 3-7-flowered: lowest flower naked, staminate or neutraL 



Glume entire. 



53. Arundo. As u. 52, but flowers all perfect. Glume bifid. 



40 



